A radiowave absorber may be used as a means for avoiding radiowave interference. Generally, a radiowave absorber is sponge made of resin such as polyurethane including carbon particles, such as carbon, and has conductivity. An installation example of a radiowave absorber includes a parabolic antenna that is used for point-to-point communication. In order not to radiate radiowaves as much as possible in the direction outside the opposing counter station, it is necessary to keep the sides lobes of the antenna low. As a measure, a constitution is often used that provides a shroud around the parabolic reflector, and affixes a radiowave absorber on the inner side of this shroud.
FIG. 13 shows the constitution of a conventional parabolic antenna 900. This parabolic antenna 900 is constituted from a reflector (parabolic reflector) 910, a shroud 920, a primary radiator 930, and a radiowave absorber 800. As a radiowave absorber, Patent Document 1 discloses a radiowave absorber constituted from a radiowave reflecting film, a resistance film, and a spacer.